In a move that civil-liberties groups hope will expand privacy protections for the digital age, the state Supreme Court declared on Thursday that police in New Jersey must first obtain a search warrant before using cellphone data to track a suspect.

Ruling unanimously in a case stemming from a 2006 burglary investigation, the justices said the use of such data violates New Jersey residents’ expectations of privacy, noting the ubiquity of cellphones in the United States and rapidly evolving technology that can now pinpoint a user’s location to within a couple of feet.

The decision is one of the first nationally to build on a 2012 U.S. Supreme Court decision that found the warrantless electronic tracking of a suspect’s car unconstitutional. Justice Sonia Sotomayor noted in a concurring opinion in that case that questions over the proper level of protection to extend to cellphone data would likely be the next major privacy flash point.

In requiring police to obtain a warrant before accessing such cellphone data, the state Supreme Court gave the information the highest level of legal protection.

It broke with the state Attorney General’s Office, which argued that the technology available at the time of the 2006 investigation did not raise privacy concerns because it allowed police only to narrow the location of the burglary suspect, Thomas W. Earls, to a square-mile area. Ultimately, police tracked him to a motel in Howell, where he was arrested. He later pleaded guilty to burglary and theft in connection with a string of burglaries in Monmouth County.

Instead, the justices declined to draw distinctions among different types of tracking, noting that cellphone data could be used to pry into individuals’ personal lives.

“With increasing accuracy, cellphones can now trace our daily movements and disclose not only where individuals are located at a point in time but also which shops, doctors, religious services and political events they go to and with whom they choose to associate,” Chief Justice Stuart Rabner wrote on behalf of the unanimous court. “Yet people do not buy cellphones to serve as tracking devices or reasonably expect them to be used by the government in that way.”

A spokesman for the Attorney General’s Offices said the agency “will implement training for New Jersey law enforcement to ensure compliance with this ruling.”

“As a practical matter, this ruling only affects future cases, and police in New Jersey already have been routinely seeking probable cause-based warrants before seeking cellphone location information,” said the spokesman, Peter Aseltine.

The decision has no bearing on efforts by law enforcement agencies to listen in on cellphone conversations, which have always required a warrant. But it highlights how technically sophisticated cellular technology has become, at times outpacing the law.

In an unusual move, the justices ordered a second round of oral arguments in the case in January, indicating the importance they were placing on the decision. They did so in part because they wanted more specific information on cellphone technology.

Thursday’s decision comes amid a national debate over recent disclosures of widespread government surveillance of telephone calls and emails. However, the high court deliberately chose not to address federal constitutional questions and instead limited its ruling to the New Jersey Constitution, which Rabner noted contains stronger privacy protections.

Still, privacy advocates hope the ruling will resonate nationally.

“It’s a very exciting decision, which recognizes electronic privacy rights far beyond the very important context behind cellphone technology,” said Rubin M. Sinins, an attorney for the American Civil Liberties Union of New Jersey and the New Jersey Association of Criminal Defense Attorneys, which filed friend-of-the-court briefs in the case. “We believe that [this] privacy interest should be held by all Americans, not just New Jerseyans, and we certainly believe these decisions are on firm ground and logical ground to explain why it’s so important.”

He said New Jersey courts have long led the way in extending electronic privacy rights, noting a case he successfully argued before the state Supreme Court five years ago that protected Internet subscriber information. Rabner wrote that unanimous decision as well.

Alan Butler, an attorney for the Electronic Privacy Information Center, a national advocacy group that filed a friend-of-the-court brief in the Earls case, called it “a critical step forward on this important privacy issue.”

It’s clear that the use of cellphone tracking has become widespread in criminal investigations.

The Attorney General’s Office reported more than 600 requests for such information from New Jersey law enforcement agencies over six months in 2012. Police obtained search warrants for the data in about 85 percent of those cases — a fact the state attributed at a hearing to an abundance of caution on the part of county prosecutors and local police departments and a 2010 law that provides increased protection for certain kinds of cellphone data.

Historical information on the use of such data isn’t available, and the justices said their ruling applied only to cases that occurred after that state law was enacted and to Earls’ burglary case.

The decision doesn’t represent the end of the line for Earls. Police used information provided by T-Mobile, Earls’ cellphone provider, to track him to a motel in Howell after obtaining an arrest warrant for him. When officers took him into custody, they noticed stolen property in his motel room.

Prosecutors sought to use the property as evidence. A trial judge ruled that the police didn’t need to obtain a search warrant before accessing his cellphone tracking information because they feared Earls posed a danger to his girlfriend, who had cooperated with authorities and with whom he had a history of domestic violence.

Though Earls pleaded guilty to burglary, drug possession and related charges in connection with the arrest, he sought to withdraw his plea after being sentenced to a seven-year prison term.

In a 2011 decision upholding Earls’ conviction, an appellate panel ruled that provisions forbidding warrantless searches in the federal and state constitutions don’t apply to certain cellphone data.

The high court overruled that decision. Noting that courts have long allowed law enforcement agencies to sidestep search warrant requirements in certain emergency circumstances, the justices sent the matter back to an appellate panel to determine whether such a situation existed in the Earls case.

Earls was released from prison several years ago, said Alison S. Perrone, his court-appointed attorney.

This article includes material from The Associated Press. Email: campisi@northjersey.com

In a move that civil-liberties groups hope will expand privacy protections for the digital age, the state Supreme Court declared on Thursday that police in New Jersey must first obtain a search warrant before using cellphone data to track a suspect.

Ruling unanimously in a case stemming from a 2006 burglary investigation, the justices said the use of such data violates New Jersey residents’ expectations of privacy, noting the ubiquity of cellphones in the United States and rapidly evolving technology that can now pinpoint a user’s location to within a couple of feet.

The decision is one of the first nationally to build on a 2012 U.S. Supreme Court decision that found the warrantless electronic tracking of a suspect’s car unconstitutional. Justice Sonia Sotomayor noted in a concurring opinion in that case that questions over the proper level of protection to extend to cellphone data would likely be the next major privacy flash point.

In requiring police to obtain a warrant before accessing such cellphone data, the state Supreme Court gave the information the highest level of legal protection.

It broke with the state Attorney General’s Office, which argued that the technology available at the time of the 2006 investigation did not raise privacy concerns because it allowed police only to narrow the location of the burglary suspect, Thomas W. Earls, to a square-mile area. Ultimately, police tracked him to a motel in Howell, where he was arrested. He later pleaded guilty to burglary and theft in connection with a string of burglaries in Monmouth County.

Instead, the justices declined to draw distinctions among different types of tracking, noting that cellphone data could be used to pry into individuals’ personal lives.

“With increasing accuracy, cellphones can now trace our daily movements and disclose not only where individuals are located at a point in time but also which shops, doctors, religious services and political events they go to and with whom they choose to associate,” Chief Justice Stuart Rabner wrote on behalf of the unanimous court. “Yet people do not buy cellphones to serve as tracking devices or reasonably expect them to be used by the government in that way.”

A spokesman for the Attorney General’s Offices said the agency “will implement training for New Jersey law enforcement to ensure compliance with this ruling.”

“As a practical matter, this ruling only affects future cases, and police in New Jersey already have been routinely seeking probable cause-based warrants before seeking cellphone location information,” said the spokesman, Peter Aseltine.

The decision has no bearing on efforts by law enforcement agencies to listen in on cellphone conversations, which have always required a warrant. But it highlights how technically sophisticated cellular technology has become, at times outpacing the law.

In an unusual move, the justices ordered a second round of oral arguments in the case in January, indicating the importance they were placing on the decision. They did so in part because they wanted more specific information on cellphone technology.

Thursday’s decision comes amid a national debate over recent disclosures of widespread government surveillance of telephone calls and emails. However, the high court deliberately chose not to address federal constitutional questions and instead limited its ruling to the New Jersey Constitution, which Rabner noted contains stronger privacy protections.

Still, privacy advocates hope the ruling will resonate nationally.

“It’s a very exciting decision, which recognizes electronic privacy rights far beyond the very important context behind cellphone technology,” said Rubin M. Sinins, an attorney for the American Civil Liberties Union of New Jersey and the New Jersey Association of Criminal Defense Attorneys, which filed friend-of-the-court briefs in the case. “We believe that [this] privacy interest should be held by all Americans, not just New Jerseyans, and we certainly believe these decisions are on firm ground and logical ground to explain why it’s so important.”

He said New Jersey courts have long led the way in extending electronic privacy rights, noting a case he successfully argued before the state Supreme Court five years ago that protected Internet subscriber information. Rabner wrote that unanimous decision as well.

Alan Butler, an attorney for the Electronic Privacy Information Center, a national advocacy group that filed a friend-of-the-court brief in the Earls case, called it “a critical step forward on this important privacy issue.”

It’s clear that the use of cellphone tracking has become widespread in criminal investigations.

The Attorney General’s Office reported more than 600 requests for such information from New Jersey law enforcement agencies over six months in 2012. Police obtained search warrants for the data in about 85 percent of those cases — a fact the state attributed at a hearing to an abundance of caution on the part of county prosecutors and local police departments and a 2010 law that provides increased protection for certain kinds of cellphone data.

Historical information on the use of such data isn’t available, and the justices said their ruling applied only to cases that occurred after that state law was enacted and to Earls’ burglary case.

The decision doesn’t represent the end of the line for Earls. Police used information provided by T-Mobile, Earls’ cellphone provider, to track him to a motel in Howell after obtaining an arrest warrant for him. When officers took him into custody, they noticed stolen property in his motel room.

Prosecutors sought to use the property as evidence. A trial judge ruled that the police didn’t need to obtain a search warrant before accessing his cellphone tracking information because they feared Earls posed a danger to his girlfriend, who had cooperated with authorities and with whom he had a history of domestic violence.

Though Earls pleaded guilty to burglary, drug possession and related charges in connection with the arrest, he sought to withdraw his plea after being sentenced to a seven-year prison term.

In a 2011 decision upholding Earls’ conviction, an appellate panel ruled that provisions forbidding warrantless searches in the federal and state constitutions don’t apply to certain cellphone data.

The high court overruled that decision. Noting that courts have long allowed law enforcement agencies to sidestep search warrant requirements in certain emergency circumstances, the justices sent the matter back to an appellate panel to determine whether such a situation existed in the Earls case.

Earls was released from prison several years ago, said Alison S. Perrone, his court-appointed attorney.

This article includes material from The Associated Press. Email: campisi@northjersey.com